Diaphragm mounting



May 8, 1934. R. E. TOLERTON 1,957,562

DIAPHRAGM MOUNTING Filed June 11, 1932 INVENTOR.

RAY E. TOLERTON.

BY m

' TORNEY Patented May 8, 1934 UNITED STATES PATENT OFFICE DIAPHRAGM MOUNTING corporation of Arizona,

Application June 11, 1932, Serial No. 616,686

8 Claims.

This invention relates to sound reproducing devices in which a sound emissive member such as a conical diaphragm is adapted to be actuated by electrical impulses or mechanical vibrations, and more particularly to a sound reproducer of the electro-dynamic type wherein a diaphragm actuating coil is disposed for axial movement in a powerful radial magnetic field.

An object of my invention is to provide a new and novel form of centering device for the actuating coil of an electro-dynamic loud speaker which will provide freedom from torsional strains and permit greater movement of the actuating coil than is possible with like devices of the prior art.

In loud speakers of the specific type referred to in which the diaphragm is flexibly supported to permit its free movement in an axial direction, and in which the coil that drives the diaphragm is also designed to have considerable amplitude of movement at some frequencies, some steps must be taken to ensure that the moving coil is accurately centered in such a manner that free axial movements are permitted without any substantial lateral displacement.

Numerous devices have been proposed such as threads attached to and adapted to radiate from the coil and be connected to a fixed abutment. Among other known centering devices may be 30 mentioned the type comprising a thin disc, the

center of which is attached to a central fixed point, having are like portions cut away in order to give flexibility, the periphery of the disc having secured thereto the truncated apical region of the diaphragm. Further it has been suggested to use a thin flat ring, adapted to embrace the coil, having outwardly extending spiral arms, the outer ends of which are fixed to relatively stationary supporting means.

40 Devices of the above character are unsatisfactory since they must inevitably stretch when motions of large amplitude take place. This strain, although of a small order, in time imparts a definite deformation or permanent set in the 45 material, or it slackens its attachments. As a result of this the arms of the centering means are too long when the diaphragm is in its normal position, and kink or buckle in one or a number of places. When this occurs, the diaphragm will not stay in its true position of rest, neither will it reciprocate unrestrainedly about this position, but tends to jump from one extreme to the other, thereby causing distortion and loss of sensiti ity. Where the spiral arms are formed either within or outside of the diaphragm a torsional movement is imparted to the driving coil when the diaphragm vibrates. This distorts the diaphragm and tends to break the coil from the diaphragm at the point of its attachment thereto.

In the preferred embodiment of my invention I form the diaphragm coil centering spider from a relatively thin sheet of flexible material, such as bakelite, fibre or other similar substance. The spider when produced in large quantities is punched from the above material by suitable dies.

In configuration my improved spider has a central annular ring from which a plurality of bifid or bifurcated arms extend substantially radially, the halves of the bifid or bifurcated arms being formed as open loops which extend on each side of and beyond a fixed abutment to which they return and are attached. This produces a flexing member of considerable length and locates the part of maximum flexing at a point removed from the diaphragm coil and beyond the stationary support to which the member is attached. One form of such a centering spider is illustrated and described in my prior Patent Number 1,820,585, dated August 25, 1931, and entitled Loud speaker.

For a better understanding of my invention reference should be had to the accompanying drawing, wherein I have shown by way of illustration and not of limitation preferred embodiments thereof.

In the drawing wherein like figures refer to like parts throughout the several views;

Figure l is a fragmentary sectional view in elevation showing my improved spider applied to the small end of a conical diaphragm,

Figure 2 is a plan view of the centering spider illustrated in Figure 1,

Figure 3 is a modified form of the spider illustrated in Figure 2,

Figure t is a view similar to Figure 1 showing a three armed spider applied to a conical diaphragm,

Figure 5 is a plan view of the spider illustrated in Figure 4,

Figure 6 is a modified form of the three point spider illustrated in Figure 5, and

Figure 7 is a diagrammatic view showing positions taken by the arms of my support when flexed.

In the drawing I have illustrated my invention as applied in the conventional way to the field structure of an electro-dynamic loud speaker having an inner pole 10 and an outer pole 11 between which an annular air gap is formed. The sound 110 reproducing diaphragm, designated by the numeral 12, is shown as having a cylindrical coil support 13 affixed to its small end and projecting therefrom so that it can be disposed in the air gap formed between the poles 10 and 11. Adjacent the air gap and mounted upon the outer pole 11 are suitable fixed abutments 14 to which the coil centering and supporting means may be secured. While these abutments 14 are shown as mounted upon the outer pole 11, it should be understood that they may be mounted upon the other parts of the speaker assembly.

As a centering and supporting means for the small end of the diaphragm 12 and its driving coil support 13, I form a spider 15 with bifid arms, the lobes or halves of which extend out on opposite sides and beyond the abutments 14 and return to their point of attachment therewith. The spider 15 is secured to the diaphragm 12 at the time the coil support is attached thereto and is generally glued in place.

In Figure 2 of the drawing, I have illustrated one form of my improved spider as having a central or annular portion 16 with oppositely disposed bifid arms or extensions 17, the arms or extensions 17 being formed by a pair of radially extending portions 18 which project outwardly a distance greater than the radial distance of the supporting abutments 14 from the coil support and bow back inwardly at a point 19 toward each other where they combine and are secured to an abutment. With this form of spider the coil support 13 will have four equally spaced radially extending centering members which will require one half as many abutments 14.

The spider illustrated in Figure 3 of the drawing is a modified form of the spider shown in Figure 2. In this embodiment the outwardly extending portions 18 of the bifid arms 17 extend parallel to each other and double back at the points 19 in the manner previously described.

In connection with the centering spiders illustrated in Figures 2 and 3, it will be noted that the outwardly projecting arms 18 extend some distance beyond the point where after doubling back they engage the abutments 14. With this structure the point of maximum flexing is disposed a considerable distance from the coil support 13 and as a result a maximum movement of the coil support is permitted with a minimum of distortion at the points 19.

In Figures 4 and 5 of the drawing, I have illus trated my invention as embodied in a three point suspension spider. In this embodiment the outwardly projecting arms, designated by the numeral 20, which form the bifid extensions 17, are disposed nearer together than in the previously described structures and extend radially outward on each side of their cooperating abutment 14 and double back at the points 19.

With a spider of this latter character, wherein three or more bifid extensions 17 are provided, the tendency for the coil support 13 to turn about the axis of the abutments is eliminated and consequently it is possible to extend the individual arms 20 of the bifid extensions 1'? outwardly to a greater extent than is possible where only two bifid extensions are used.

In Figure 6 which illustrates a modified form of the spider shown in Figure 5 the individual arms, designated by the numeral 21, that form the bifid extensions 17, bow outwardly along a line tangent with the annular portion 16 of the spider. In operation this form of spider functions in the same manner as will the spider of Figure 5, the

point of maximum flexing of the arms 21 being at the points 19.

In Figure '7, I have diagrammatically illustrated the coil support 13 of Figure 3, in its two extreme positions, with the spider 15 in its flexed condition. From this figure of the drawing it will be noted, as previously stated, that the point of maximum flexing in the centering spider will be at the outer extremities of the spider.

In the usual type of external spider, the diaphragm is secured to the inner portion of the spider and the outer extremity of the spider is mounted upon the stationary abutments. If the inner portion of the spider and the abutment engaging portions are connected by arms which do not actually double back on themselves, a movement of the diaphragm coil will necessitate either an actual stretching of the material or a radial movement of either the inner circle or the points of support, or else, as in the case of spirally disposed connecting arms, a circular movement of the coil support and apical region of the diagram. However, if the connecting arms between the diaphragm and the abutments are zigzagged or doubled back in a radial direction, as outlined above, it will be seen that the points of reversal of direction of these zigzag arms will act as pivotal points and allow a relative motion between the coil support and the abutments without necessitating any radial or circular motion of either the coil support or abutments.

From the above it will be seen that no part of the spider (or its attachments) is subjected to undue stress during the reciprocation of the coil support and diaphragm, and thus great freedom of movement will be permitted to the diaphragm.

The spider moreover may be made light and easily flexible without losing its effectiveness and will endure almost indefinitely without being strained to the extent of suffering a permanent set.

While I have, for the sake of clearness and in order to disclose my invention so that the same can be readily understood, described and illustrated specific devices and arrangements, I desire to have it understood that this invention is not limited to the specific means disclosed but may be embodied in other ways that will suggest themselves, in view of this broad disclosure, to persons skilled in the art. It is believed that this invention is broadly new and it is desired to claim it as such so that all such changes as come within the scope of the appended claims are to be considered as part of this invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is- 1. In a sound reproducing device of the character having a conical diaphragm adapted to be propelled from its small end and flexibly supported at its periphery, the combination of a conical diaphragm, a coil support affixed to the small end of said diaphragm, an inner and an outer magnetic field pole forming an air gap in which said coil support may move, a stationary abutment adjacent said air gap, and a centering means secured to said coil support for maintaining said support centrally in said air gap without interfering with axial movement thereof, said means having a radially disposed bifid extension, the halves of which bow outwardly in a radial direction beyond said abutment and double back toward each other and engage the abutment adjacent the air gap.

2. In a sound reproducing device of the character having a conical diaphragm adapted to be driven from its small end and flexibly supported at its periphery, the combination of a conical diaphragm, a coil support affixed to the small end of said diaphragm, an inner and an outer magnetic field pole forming an air gap in which said 0011 support is disposed, fixed abutments adjacent said air gap, and means engaging said abutments secured to said coil support for maintaining said coil support centrally in said air gap without interfering with axial movement thereof, said means having radially disposed outwardly extending bifid arms, the halves of which bow outwardly in a radial direction beyond said abutments and double back toward each other and engage said abutments.

3. In a sound reproducing device of the character having a conical diaphragm adapted to be driven from its small end and flexibly supported at its periphery, the combination of a conical diaphragm, a coil support affixed to the small end of said diaphragm, an inner and an outer magnetic field pole forming an air gap in which said coil support is disposed, a plurality of abutments adjacent said air gap, and a centering spider for maintaining said coil support centrally in said air gap without interfering with the axial movement thereof, said spider having a plurality of symmetrically disposed arms arranged in pairs which extend substantially radially outwardly from the coil support beyond said abutments and double back in a substantially radial direction toward each other to engage said abutments.

4. A centering spider for the diaphragm actuating coil of an electro-dynamic loud speaker, comprising a flat member of flexible material having a central portion adapted to be secured to a diaphragm and a plurality of bifid arms, the halves of which extend outwardly adjacent and along opposite sides of fixed abutment and double back to said abutment so as to form symmetrically disposed resilient loops on each side of said abutment which will flex at a point outwardly beyond the abutment and permit axial movement of the diaphragm actuating coil.

5. A centering spider for the diaphragm actuating coil of an electro-dynamic loud speaker, comprising a flat member of flexible material having a central portion adapted to be secured to a diaphragm and a plurality of pairs of arms, the

individual arms of which extend outwardly along opposite sides of and outwardly beyond a fixed abutment and double back to said abutment so as to form resilient loops on each side of said abutment which will flex at a point radially beyond said abutment and permit axial movement of the diaphragm actuating coil.

6. In combination with a conical diaphragm, a coil at the small end of said diaphragm for driving same, a field structure having an annular air gap in which said coil is disposed, a plurality of abutments adjacent said air gap, and a spider for retaining said coil centrally in said air gap without interfering with its axial movement, said spider comprising a central annular portion which engages the diaphragm having a plurality of radially extending bifurcated arms formed by a pair of symmetrically disposed loops which extend radially outward from said central annular portion beyond and double back to a cooperating abutment.

7. In combination with a conical sound reproducing diaphragm, a coil at the small end of said diaphragm, a field structure having an air gap in which said coil is disposed, a plurality of stationary supports adjacent said air gap, and means cooperating with said stationary supports for retaining said coil centrally in said air gap, comprising a fiat flexible member disposed in a plane at right angles to the axis of the conical diaphragm having radially extending arms which project outwardly in pairs one arm on each side of each of said stationary supports and double back toward each other and engage a cooperating stationary support.

8. A centering support for the small end of a conical diaphragm of an electrodynamic loud speaker, comprising a flat member or flexible material having a portion adapted to be attached to the diaphragm and another portion adapted to be secured upon a stationary support, said member having radially disposed bifid connecting arms extending between said portions which double back upon each other along substantially radial lines and have a length at least twice as great as the radial distance between the diaphragm and said stationary support.

RAY E. TOLERTON. 

